1. Field of the Invention
The present invention relates to a design variable optimization system and a design variable optimization method for determining a specific design variable from among numerous design variables according to a particular evaluation criterion, for a design article whose performance varies with change of the design variable.
2. Related Background Art
There are well-known design variable optimization systems for determining a specific design variable from among numerous design variables according to a particular evaluation criterion, for a design article whose performance varies with change of the design variable. Such design variable optimization systems normally include a performance value calculating section for carrying out an analysis (simulation) on a design article for a fixed time using each of the design variables and for calculating a performance value for evaluating the performance of the design article using each of the design variables, based on the result of the analysis. Known systems also include a design variable determining section for applying each of the performance values calculated by the performance value calculating section, to the foregoing evaluation criterion, thereby determining an optimal design variable from among the numerous available design variables.
For example, let us consider designing an article such as a pillar of a car. The pillar of a car is a design article whose so-called “upper interior head impact protection requirements” varies according to several design variables, e.g., the thickness of ribs located on the pillar, the thickness of the outer wall of the pillar, and the interval between the ribs of the pillar. Namely, when the pillar is designed in a design variable optimization system, the aforementioned performance value calculating section first calculates by simulation a dynamic change of acceleration within a fixed time during a collision of an object (e.g., Free Motion Headform) with the pillar using a combination of each of the design variables, i.e., variously changed values of the thickness of the ribs on the pillar, the outer wall thickness of the pillar, and the intervals between ribs on the pillar. The performance value calculating section further calculates an HIC(d) as a performance value for evaluating the upper interior head impact protection requirements of the pillar of the car, using a calculated dynamic change of acceleration. The design variable determining section then compares the various HIC(d) calculated by the performance value calculating section, and determines a combination of rib thickness on the pillar, outer wall thickness of the pillar, and rib interval on the pillar that provides a minimum HIC(d), thus achieving an optimal design for the pillar.